Device for verifying security features

ABSTRACT

The invention relates to a device ( 20 ) for making security elements visible, which are provided in an object ( 8 ) and have at least one photoluminescent segment that is characterized by having a linearly polarized absorption. The aim of the invention is to obtain a device of this type that has a particularly simple and compact design. To this end, at least one UV light source, which is provided in the form of a UV diode ( 18 ), and at least one polarization filter ( 4 ) are arranged so that the light of the light source ( 18 ) is linearly polarized ( 12 ) by the polarization filter ( 4 ) and, in a dark space ( 17 ), strikes the object ( 8 ) with respect to the photoluminescent segments provided therein, and photoluminescent light ( 16 ) in the visible range emitted by the segment can be observed through an observation opening ( 10 ).

TECHNICAL FIELD

The present invention relates to a device and a method for revealingsecurity elements that are present in an object and that have at leastone photoluminescent segment which is characterized by linearlypolarized absorption.

A security element of this type has been described, for example in WO00/19016.

PRIOR ART

It is generally known that, for security papers and security articlesquite generally, for example for banknotes, checks, stocks and shares,bonds, identity papers, passports, drivers' licenses, entry cards,postage stamps and similar documents or, for example, for bank cards,credit cards and the like, use is made of security elements which havethe purpose of preventing or making difficult the forgery of theseobjects by an unauthorized persons (R. van Renesse, “Optical DocumentSecurity” (1997), Artech House, Boston). Equally, such security elementsare used for the purpose of identifying the authenticity or validity ofobjects or, quite generally, permitting or making easier theidentification of objects.

For example, the use of security threads or strips, which, for example,can consist of plastic coated with metal, in security papers iswidespread, in particular for the use in banknotes and similarsecurities. If these security threads or strips are, for example,embedded in the security paper and the latter is subsequently printed,however, these security elements cannot readily be detected if theobject is observed in reflection. However, they appear as a dark shadowwhen the object is transilluminated and is therefore observed intransmission.

In particular in order to ensure the security against forgery ofsecurity articles, for example of security papers, in recent times manyproposals have been made relating to providing security elements withspecific characteristics, so that not only the presence of securityelements for itself but, in particular, also the presence of specificcharacteristics is intended to guarantee the authenticity of the securedobject (U.S. Pat. No. 4,897,300; U.S. Pat. No. 5,118,349; U.S. Pat. No.5,314,739; U.S. Pat. No. 5,388,862; U.S. Pat. No. 5,465,301, DE-A1,446,851; GB 1,095,286). For instance, DE-A 1,446,851 has disclosed asecurity thread which has a multicolored microprint; in this case, theprinting ink can also be fluorescent. The areas printed in differentcolors are so small or so close together in this thread that they cannotbe distinguished by the naked eye and therefore appear to the observeras a single-colored pattern. On the other hand, the microprint and itsdifferent colors can be detected with the aid of a magnifying glass or amicroscope.

Furthermore, reference is made to WO 00/19016, in which a security paperor quite generally security articles are described which contain atleast one security element that has at least one photoluminescentsegment which is distinguished by linearly polarized photoluminescenceand/or linearly polarized absorption. In this document, it is pointedout that linearly polarized excitation light, which, for example, can begenerated by an external light source in conjunction with a linearpolarizer, is absorbed to different extents by the segment, depending onthe orientation of the polarization axis of the segment and thepolarization direction of the excitation light, which can lead to a highlight/dark contrast when observed by the naked eye.

Furthermore, reference is made to U.S. Pat. No. 5,892,239, whichdescribes an instrument for the identification of security features on asecurity document, in which unpolarized light is used for illuminationand polarization is used during the detection. A similar device isdescribed by U.S. Pat. No. 4,990,790.

In connection with such security features having photoluminescentsegments with polarizing properties, there is a need for devices for thedetection or verification of such security features. Such devices are tohave a high resolution and good contrast and, at the same time, shouldbe capable of implementation in a technically simple and in particular avery compact manner, that is to say should be resistant, easy to carryand capable of inexpensive production, in order to permit widedistribution.

SUMMARY OF THE INVENTION

Accordingly, the invention is based on the object of providing a methodand, respectively, a device for revealing security elements present inan object, the security elements to be observed having at least onephotoluminescent segment which is characterized by linearly polarizedabsorption. The segment can additionally have polarized emission in thevisible range.

The object, for example a banknote, can also contain further additionalsecurity features, however, which if appropriate can be verified withthe same device.

At the same time, the device is to be very compact and to permit easyand reliable detection of the security elements without having to fallback on a complicated and possibly temperamental design.

This object is achieved in that at least one UV light source, inparticular preferably in the form of a UV diode, and at least onepolarization filter are arranged in such a way that the light from thelight source is linearly polarized by the polarization filter, strikesthe object and, respectively, the photoluminescent segments presenttherein in a dark chamber, and photoluminescent light from the segmentin the visible range can be observed through an observation opening.

In other words, the nub of the invention is to provide in a complexdesign, in particular with the aid of one or more UV diodes, which canbe extremely small and have a low power requirement, an instrument forverifying polarizing (in particular selectively absorbing only light ofa specific polarization direction) and fluorescent security features,which can be produced inexpensively, is inexpensive in operation (simplebatteries, low current consumption) and which is barely susceptible tofaults. This is because it has transpired that, surprisingly, UV diodeshave a light intensity which is entirely sufficient to build such acomplex analysis instrument. Reliable observation even in daylight isensured in this case by the arrangement of a dark chamber, in which theobject having the security feature is illuminated by a UV light beam,and which dark chamber has a specific observation opening.

Instead of the UV diodes, use can also be made of another UV lightsource, an appropriate laser light source with emission in the correctUV range, but also conceivable are broadband light sources, in front ofwhich there is connected an appropriate filter which allows only UVradiation to pass through. If appropriate, a filter of this type canalso be a polarization filter at the same time, which in a correspondingway permits only UV radiation of a specific linear polarizationdirection to pass.

For this purpose, the observation opening is preferably configured insuch a way that the region of the eye can be placed directly on theobservation opening (if appropriate provided with a corresponding eyesupport, for example in the form of a rubber ring), in such a way thatas little light as possible can get into the dark chamber.

According to a first preferred embodiment of the invention, the UV diodeis a diode which emits light in the UV range from 300 to 400 nanometers,in particular in the range from 350 to 385 nanometers, the UV diodeproviding an optical output in the range from 0.5 to 20 mW, inparticular preferably from 1 to 5 mW, given a current of 15 to 20 mA androom temperature.

The UV diode can, however, also emit light in a broader range,specifically in the UV range from 180 to 500 nanometers. Depending onthe security feature used, a broader emission characteristic can beadvantageous. Powers of the UV diodes outside the range specified abovecan also be used but higher powers are typically correspondinglyassociated with a higher current consumption, which has a detrimentaleffect on the lifetime of a battery used, and lower powers typicallylead to a comparatively low light intensity and, accordingly, reduceddetectability of the desired effect. However, the latter can possibly becompensated for either by means of a higher concentration (focusing) ofthe light beam or, for example, by means of electronic amplification ofthe signal reflected from the object.

Diodes of this type for the UV range are currently available in anextremely small design, for example with diameters in the range from 3to 7 mm and a height of 3 to 10 millimeters, which makes them suitablefor the use described here. In particular, it is in this way possible toconstruct the device such that it can be handled as a hand-heldinstrument and, for example, in the form of a small pen, it beingpossible, for example, for the object to be illuminated with one endwith the aid of a UV light beam oriented substantially parallel to theaxis and to be observed through an observation opening. A hand-heldinstrument of this type can be produced at low cost and, in particular,can be carried easily, for example in a vest pocket, which permitsuniversal and mobile use as an analytical instrument.

In order to increase the quality of the observation further, accordingto a further preferred embodiment of the present invention, theobservation can take place through a filter which substantially does notpermit light in the wavelength range of the UV diode to pass, whilelight in the wavelength range of the visible photoluminescent light fromthe segment can pass substantially unimpeded. A filter of this type cansimply be mounted in front of the observation opening and increases thequality of the observation as a result of the elimination of interferingsignals. It is also possible, instead of a band-selective filter, toprovide a rigid or possibly likewise mobile polarization filter in frontof the observation path as well, so that only linearly polarized lightemitted by the security feature in a specific polarization direction isobserved. In this way, interfering signals are suppressed still moreefficiently and observation is simplified and improved.

If the polarization filter is a polarization filter which, both in theUV range and in the visible range, lets through light only of a specificpolarization direction, then a single such polarization filter can beplaced both in the light beam of the light shone in or in the light pathbetween object and observer. Thus, on one side the light shone in islinearly polarized and light emitted by the appropriately configuredobject and likewise linearly polarized is additionally filtered beforethe observation. In this way, the signal-to-noise ratio can be improvedand, additionally, it may also be possible to verify security featureswhich, although they exhibit no linearly polarized absorption, exhibitlinearly polarized emission.

According to a further preferred embodiment, the polarization filter forobservation can be rotated about an axis perpendicular to the plane ofthe polarization filter. While the light/dark effect occurring as aresult of the polarization effects of the security features in the caseof a rigid polarization filter becomes visible only if the hand-heldinstrument is rotated about an axis substantially perpendicular to theplane of the polarization filter, when there is a rotatable polarizationfilter present in the housing this effect can be brought about verysimply and reliably. In this case, this rotation of the polarizationfilter can be provided via appropriate means, for example in the form ofa pen to be moved, directly by hand or else with the aid of atransmission mechanism, in particular the rotation of the filter throughat least 180 degrees preferably being possible. The transmissionmechanism is preferably a possible way of setting the polarizationfilter rotating via a simple knob movement, for example with the thumbon one end of the pen. This can, for example, be carried out counter toa spring force, so that the polarization filter is rotated through atleast 180 degrees by pressing the knob down and, when the knob isreleased, said polarization filter automatically rotates back into itsoriginal position again on account of the spring force. Mechanisms ofthis type can be implemented, for example, via a spiral spring andsuitably deflected grooves. Alternatively, it is also possible to rotatethe polarization filter with the aid of a small motor, it being possiblefor the polarization filter to be rotated with a rotation frequency inthe range from 0.2 to 5 Hz, in particular preferably with a rotationfrequency from 0.5 to 2 Hz. There can be an ability to rotatecontinuously.

Another preferred embodiment of the present invention is characterizedin that the device is configured in the form of a pen which has acylindrical housing to accommodate at least one battery and a diode anda lower cylindrical housing part, possibly with a larger diameter, thelower housing forming a cavity as a dark chamber with an observationopening, with which the object to be observed can be covered, theinstrument in particular preferably having a length of less than 10centimeters and, at its thickest point, a diameter of less than 2.5 cm.The observation opening is preferably an opening in the lower housingpart in the form of a segment cutout extending from the lower edge ofthe lower housing part with an opening angle in the range from 90 to 150degrees with a height of less than 1.5 cm.

The desired flip-flop effect can, as mentioned above, be produced by thehand-held instrument being rotated by the user about the observationaxis or else by means being provided in order to rotate the polarizationfilter or filters in such a way that the polarization direction of thelight aimed at the object is rotated. Alternatively, however, accordingto another preferred embodiment of the present invention, it isadditionally possible to provide 2 or else more groups of at least oneUV diode in each case, preferably of 2 UV diodes in each case, and toactivate these groups in accordance with a specific pattern, each groupthrowing light with a different polarization direction onto the object.This can be implemented, for example, by 2 groups irradiating the objectin a predefined, alternating manner, the first group throwing a cone oflight with a first polarization direction onto the object, and thesecond group a cone of light with a second polarization direction, andthe first polarization direction being aligned substantiallyperpendicular to the second polarization direction. By means of thisalternate switching of the two groups on/off, a flip-flop effect isproduced, which is similar to that which is produced when thepolarization filter is rotated (for example continuously). However, theadvantage of this solution is that there are no mechanical parts;instead the effect is produced exclusively by means of appropriateelectrical or electronic activation of different groups.

It is also possible to provide 3 groups, for example, one group thenthrowing a polarization direction of zero degrees onto the object, asecond group throwing a polarization direction of 45 degrees onto theobject and a third group a polarization direction of 90 degrees. Otherdivisions are of course likewise possible, for example four groups ineach case and polarization directions of zero, 30, 60, 90 degrees(30-degree section) or even in sections of 5, 10 or 15 degrees. Thus, toa certain extent, the rotation of the polarization filter can besimulated without having to have moving mechanical parts. The individualgroups have to be activated appropriately sequentially. Of course, inthe case of a higher number of groups, more UV diodes have to bearranged whereas, in the case of an arrangement of only 2 groups, forexample security features having a relative arrangement of 45 degreesexhibit no flip-flop effect or only a very weak flip-flop effect,security features of this type can likewise be visualized well in thecase of 3 groups, for example.

If, for example, 2 groups are provided, then the UV diodes areadvantageously switched alternately on and off in groups, the changebetween the two groups being carried out at a frequency of 0.2 to 5 Hz,in particular preferably at a frequency of 0.5 to 2 Hz. If there aremore than 2 groups, then these will be cycled one after another at acorrespondingly higher speed, the intention being for the group at zerodegrees and that at 90 degrees to be activated at the frequencyspecified above.

Alternatively, it is possible not to control the UV diodes in a simpleon/off method but to activate these with a corresponding curve. Forinstance, the UV diodes of the 2 groups can be activated with asubstantially sinusoidal intensity profile, the phase shift between the2 groups being substantially 90 degrees. Activating the two groups inaccordance with this pattern to a certain extent simulates the rotationof a polarization filter in front of all the diodes or, respectively,rotation of the polarization direction. Of course, appropriateactivation in the case of more than 2 groups is possible and may beexpedient.

An advantageous development of the abovementioned embodiment consists inthere being two groups of respectively two UV diodes, in each case UVdiodes belonging to one group being arranged opposite each other inrelation to the observation axis and illuminating the object obliquelyfrom above, for example, and the two groups being arranged to bedisplaced by 90 degrees around the observation axis. In this way, acompact arrangement of the UV diodes at the side of the observation pathis possible and, in addition, in this way appropriately all orthogonallyaligned polarization filters can simply be aligned in front of therespective group. In addition, the result is comparatively homogeneousillumination of the object and the illumination of the object is inprinciple similar in the case of activation of the first or the second(nth) group. Thus, effects which appear similar to the actually desiredflip-flop effect but which can arise merely as a result of the alternateswitching of the two groups and not because of the polarization effectscan be avoided in an optimum way.

In principle, the procedure is, for example, such that a polarizationfilter is arranged in front of each UV diode, the orientation of thepolarization direction of the polarization filters of the first groupbeing aligned substantially perpendicular to the orientation of thepolarization direction of the polarization filters of the second group.However, it is also possible to provide one polarization filter for eachgroup or else, according to a further preferred embodiment, it ispossible to provide a single polarization filter for all the groups, itthen being necessary for this polarization filter to have appropriatecharacteristics such that, depending on the group, differentpolarization directions are incident on the object. This can beimplemented, for example, by a cylindrical polarization filter beingarranged between object and UV diodes, the axis of the cylindricalpolarization filter substantially coinciding with the observation axis.A polarization filter of this type can perform this task if it permitsonly UV light which has a polarization direction parallel to the majoraxis of the cylinder to pass. A cylindrical polarization filter of thistype which, for example, can consist of a rolled polarization film, canbe used in combination with 2 groups of UV diodes but also incombination with any desired higher number of UV diodes if the latterare distributed appropriately over the circumference.

A further preferred embodiment of the present invention is characterizedin that a holding arm and an observation tube are provided, theobservation tube being aligned substantially at right angles to theholding arm.

Instead of or in addition to a filter, as has already been describedabove, according to a further preferred embodiment, the observation canbe carried out through a lens, in particular preferably through amagnifying glass, that is to say a lens or a magnifying glass can beplaced in front of or in the observation opening.

A further-reaching improvement in the visualization of the effects withappropriate electronic filtering possibilities, if appropriate, can beimplemented by the observation being carried out by means of electronicaids, in particular in the form of a recording device such as a camera,in particular a digital camera, if appropriate in combination with acorresponding electronic visualization means such as a display.

Furthermore, it is possible to arrange in the observation axis apolarization filter which, in particular, preferably substantially doesnot permit light in the wavelength range of the UV diode to pass, whilelight in the wavelength range of the photoluminescent light from thesegment can pass substantially only in a manner filtered with respect toits polarization direction. This arrangement is particularlyadvantageous when there are security elements which, in addition,exhibit linearly polarized emission. In addition, in this way it is alsopossible to verify photoluminescent security features which exhibit nolinearly polarized absorption but only linearly polarized emission. Afilter of this type can be rotated mechanically, if appropriate.

As already mentioned at the beginning, the device or the hand-heldinstrument can additionally have means for verifying other securityfeatures in the object. Such security features can be of an extremelywide range of types, for example magnetic, electric, optical, electronicor electro-optical features, for example selected from the groupcomprising bar codes, magnetic strips, conductivity,electroluminescence, photoluminescence, up-conversion (anti-Stokes),infrared signatures, electronically readable texts, also includinginfrared text (OCR text), X-ray fluorescence features, etc.

Preferred embodiments of the device according to the invention emergefrom the independent claims.

The present invention also relates to a method of revealing securityelements that are present in an object and that have at least onephotoluminescent segment which is characterized by linearly polarizedabsorption. In this case, the method is characterized in that light fromat least one light source in the form of a UV diode is linearlypolarized by at least one polarization filter, is incident on the objector, respectively, on the photoluminescent segments present therein in adark chamber, and photoluminescent light in the visible range from thesegment is observed through an observation opening. In particular, themethod is carried out by using a device as described above.

Further preferred embodiments of the method according to the inventionemerge from the independent claims.

BRIEF DESCRIPTION OF THE FIGURES

The invention is to be explained in more detail below using exemplaryembodiments and in conjunction with the drawings, in which:

FIG. 1 a) shows a perspective view of a hand-held instrument obliquelyfrom below; b) shows a view from below with an indication of the abilityof the polarization filter to rotate; c) shows a front view of thehand-held instrument with a view of the observation opening; d) shows aside view of the hand-held instrument with an illustration of theinternal parts and an illustration of the observation; and

FIG. 2 a) shows a view of a further hand-held instrument from below; b)shows a view of the hand-held instrument from above; c) shows a viewfrom the front; d) shows a perspective view from below; e) shows aperspective view from above; f) shows a section along the line A-A inFIG. 2 b); g) shows a schematic view from above of the structure of UVdiodes and rolled polarization filter.

PREFERRED EMBODIMENTS OF THE INVENTION

FIG. 1 a) shows a perspective view of the hand-held instrument 20obliquely from below. The hand-held instrument comprises a cylindricalhousing 1, in which one or more batteries (for example, here, 3 buttoncells from VINNIC of the alkaline cell L1154 type; IEC design: LR44;diameter: 11.6 mm; height: 5.4 mm; voltage: 1.5 V; capacity: 164 mAh;standard current: 0.22 mA; weight: 1.88 g) can be accommodated, andwhich can be closed at the upper end by a screw-on cover 9. Also presenton the cylindrical housing part is a switch 13, with which the UV lightcan be switched on and off. The cylindrical housing 1 has a diameter of1.3 cm. At the lower end, there is arranged a lower housing part 2,which has a larger diameter of 2 cm. The lower housing part is fixed tothe cylindrical housing part 1 by grub screws 6. Arranged in theinterior of the lower housing part 2 and, respectively, at the end ofthe cylindrical housing part 1 is the UV light source, and also thepolarization filter 4, which is oriented at right angles to the axis 19of the hand-held instrument 20. The polarization filter 4 is held in amount 5 and has a substantially round form. Suitable linear polarizationfilters are commercially available UV polarization filters, in practicalterms, use was made of a filter from Polaroid under the trade name“HNP′B linear ultraviolet*”, with a spectral range of 275-750 nm(delivered size of 100×100×0.15 mm). In this case, the mount 5 ismounted such that it can be rotated about the axis 19 of the hand-heldinstrument and, in order to rotate the polarization filter 4, a pin 7 isfixed to the mount 5, which pin 7 projects outward through acorresponding slot-like opening in the lower housing part 5 and can berotated by hand in order to view the light/dark effect of the polarizingsecurity features as the polarization filter is rotated. In thisspecific case, the filter can be rotated through 180 degrees, but it isalso possible to provide for the pin 7 a slot which permits an abilityto be rotated by up to 270 or more degrees. In addition, it is possibleto provide a spiral spring, so that the filter, after being rotated inone direction, returns automatically into the original position again.

It is also possible to set the polarization filter 4 rotating with amotor or else to provide a mechanism in which the polarization filter 4can be rotated via a knob which is arranged in the region of thescrew-on cover 9, for example, and can be operated with the thumb.

The lower housing part 2 at the lower end of the hand-held instrument 20is formed as a tube, so that a dark chamber 17 is formed at the bottom,with which the object 8 to be observed can be covered. This preventsdaylight interfering with the observation. The cone of light 12 whichoriginates from the UV diode 18 and is linearly polarized by thepolarization filter 4 passes along the axis 19 of the hand-heldinstrument into this dark chamber 17 and strikes the object 8 for thepurpose of observation. The lower housing end 2 has an observationopening 10, which is configured in the form of a lateral cutout. Thisobservation opening 10 can either be completely open or else canadditionally be covered with a UV filter and/or with a lens, for examplea magnifying glass, in order to improve the observation.

FIG. 1 b) shows a view into the dark chamber 17 from below. In thiscase, in particular the range 14 of the rotation of the polarizationfilter 4, as can be swept over by hand via the pin 7, is indicated by adouble arrow. In addition, it is possible to see that the polarizationfilter 4 does not necessarily have to be mounted in a circular mount 5.

FIG. 1 c) shows a front view of a hand-held instrument 20. In this case,it is possible to see how the object 8 is covered by the lower housingpart 2 for observation, so that the part of the object 8 which is to beexamined is covered by the dark chamber 17 and in this way the daylightis effectively shielded. The observation is carried out through theobservation opening 10. The entire device 20 has a height of 9 cm andcan therefore easily be carried along in a vest pocket or the like.

For the purpose of analysis of an object 8 having security features, theobject is placed on a flat surface and the hand-held instrument isguided over the object in such a way that the object is covered by thelower housing part 2. In the process, care should be taken that nointerfering light can get into the interior 17 laterally between theobject and the underside of the housing and in this way diminish thequality of the observation.

Finally, FIG. 1 d) shows a side view of the hand-held instrument. Here,it is indicated how the observer 15 observes the light 16 emitted by thesecurity features in the visible range through the observation opening10. In addition, the arrangement of polarization filter 4 and diode 18in the interior of the hand-held instrument 20 is indicated dashed. TheUV diode 18 is diodes such as can be obtained, for example, fromRoithner Lasertechnik, A-1040 Vienna under the designations RLT 370-110(about 1 mW power on the major axis of the diode with a beam divergenceof 110 degrees) and RLT 370-10 (about 0.75 mW power on the major axis ofthe diode with a beam divergence of 10 degrees, this model was used inthe present exemplary embodiment on account of the focusing of thebeam). These diodes emit light in the wavelength range from 350 to 400nanometers, the maximum of the intensity being located at about 370nanometers (spectral width at half height about 12 nanometers). Thediodes are free of visible light. The powers specified result at 25degrees Celsius and with a DC voltage of 3.9 V at 10 mA. These are inboth cases GaN diodes, in which a lens is connected in front. Likewisepossible are UV diodes based on GaN such as are offered by Toyoda GoseiCo. Ltd under the trademark “Purple”, for example with the typedesignations E1L5M-3P0AP-02 and E1L5M-4P0A2-01 and E1S09-0P0AP-02(spectral range from 370 to 420 nanometers with a maximum at 385nanometers, with a power in the range from 1 to 20 mW at roomtemperature).

FIG. 2 shows a further exemplary embodiment to illustrate the presentinvention. In this case, FIGS. 2 a) to 2 c) show views from threespatial directions, and FIGS. 2 d) and 2 e) show perspective viewsobliquely from below and obliquely from above. In this case, identicaldesignations in each case designate identical constituent parts.

The hand-held instrument of this exemplary embodiment is to a certainextent L-shaped, the instrument firstly being held by one of them, theholding arm 26, and secondly being placed on an object, such as abanknote or another object with appropriate security features. The otherlimb of the hand-held instrument is aligned orthogonally with respect tothe holding arm 26 and comprises an observation tube 21. The observationtube 21 has an eye support 22, which is configured in a similar way tothat encountered in telescopes or cameras. This is, for example, aperipheral rubber lip, on which the region around the eye can be placed.As a result, the dark chamber 17 that is present is not disrupted bylight incident on the observer side.

Arranged in the housing of the holding arm 26 are batteries 29, whichare accessible via a cover 25. This cover 25 is arranged on theunderside of the hand-held instrument 20, where there is also a loweropening 24 on the observation axis, through which opening 24 the object8 to be verified is viewed through the observation opening 10 duringviewing.

On the upper side of the holding arm 26 there are the operating elementsand the control elements. The operating elements are, firstly, a switch28 for switching the UV diode 18 on. Additionally located there is afurther switch 31, via which alternating activation of different groupsof UV diodes can be triggered.

LEDs are additionally arranged on the upper side of the holding arm 26as control elements, firstly for the state of the batteries 29 andsecondly a control lamp which indicates whether the UV diodes areswitched on.

FIG. 2 f) shows a vertical section through the hand-held instrumentaccording to the line A in FIG. 2 b). On one side, it is possible to seehere that lenses 23 are arranged in the observation path. These lenses23 enlarge the object 8 observed through the observation opening 10 andthrough the lower opening 24. This is advantageous in particular, forexample in the case of mottled fibers which, under certaincircumstances, can be quite small.

In addition, the arrangement of the UV diodes 18 can be seen in FIG. 2f). The UV diodes 18 are arranged at the side of the observation pathand irradiate the object 8 obliquely from above. In this case, the UVlight 12 passes through a cylindrical polarization filter 30. The axisof this cylindrical polarization filter 30 is arranged parallel to theobservation axis, and the polarization filter 30 allows only UV lightwhich has a polarization direction parallel to the observation axis topass.

If, then, as illustrated in FIG. 2 g) in a schematic view from above,the UV diodes 18 are arranged around this cylindrical polarizationfilter 30, then the UV light falling on the object 8 will in this casehave a first polarization direction for the oppositely arranged UVdiodes 18 a of a first group (cf. arrows in FIG. 2 g)) and a secondpolarization direction, which is oriented at right angles to the firstpolarization direction, for the oppositely arranged UV diodes 18 b of asecond group. Thus, in a very simple way, by using a single polarizationfilter 30, it is possible for UV diodes 18 from different groups 18 aand 18 b to throw linearly polarized light 12 a and 12 b of orthogonalpolarization direction onto the object 8.

The two groups 18 a and 18 b are now switched alternately on and off, sothat in each case only UV diodes of a single group light up the object.Thus, alternating light beams which have a linear polarization directionof 0 and, respectively, 90 degrees in an alternating manner strike theobject. A security feature for example whose polarized absorptiondirection is oriented parallel to the polarization direction of thelight beam 12 a will appear light, for example, when the group 18 a isactivated but, at the instant at which the second group 18 b illuminatesthe object 8, such a security feature will appear dark. In this way, aflip-flop effect can be produced as if polarization filters wererotated.

LIST OF DESIGNATIONS

-   1 Cylindrical housing-   2 Lower housing part-   3 Retaining ring-   4 Polarization filter-   5 Mount for polarization filter-   6 Grub screw-   7 Pin for rotation of polarization filter-   8 Object having security feature-   9 Screw-on cover-   10 Observation opening in 2-   11 Lower edge of 2-   12 Cone of light (polarized UV light)-   13 Switch-   14 Rotation of polarization filter via 7-   15 Observation-   16 Light emitted by security feature-   17 Dark chamber-   18 UV diode-   19 Axis of 20-   20 Hand-held instrument-   21 Observation tube-   22 Eye support-   23 Lenses-   24 Lower opening-   25 Cover of battery compartment-   26 Holding arm-   27 LED-   28 On/off switch-   29 Battery-   30 Polarization filter-   31 Flip/flop on/off switch

1. A device (20) for revealing security elements that are present in anobject (8) and that have at least one photoluminescent segment which ischaracterized by linearly polarized absorption, characterized in that atleast one UV light source, in particular preferably in the form of a UVdiode (18), and at least one polarization filter (4, 30) are arranged insuch a way that the light from the light source (18) is linearlypolarized (12) by the polarization filter (4), strikes the object (8)and, respectively, the photoluminescent segment present therein in adark chamber (17), and photoluminescent light (16) from the segment inthe visible range can be observed through an observation opening (10).2. The device (20) as claimed in claim 1, characterized in that the atleast one UV diode (18) is a diode which emits light in the UV rangefrom 180 to 500 nanometers, preferably from 300 to 400 nanometers, inparticular in the range from 350 to 380 nanometers, and in that the UVlight source or UV diode (18) preferably provides an optical output inthe range from 0.5 to 20 mW, in particular preferably from 1 to 5 mW,given a current of 15 to 20 mA and room temperature.
 3. The device (20)as claimed in claim 1, characterized in that the device (20) can behandled and is constructed in the form of a hand-held instrument suchas, for example, in the form of a small pen, it being possible, forexample, for the object (8) to be illuminated with one end with the aidof a UV light beam oriented substantially parallel to the axis (19) andto be observed through an observation opening (10).
 4. The device (20)as claimed in claim 1, characterized in that the observation can takeplace through a filter which substantially does not permit light in thewavelength range of the UV light source or UV diode (18) to pass, whilelight in the wavelength range of the visible photoluminescent light (16)from the segment can pass substantially unimpeded.
 5. The device (20) asclaimed in claim 1, characterized in that the polarization filter (4)for observation can be rotated about an axis perpendicular to the planeof the polarization filter (4).
 6. The device (20) as claimed in claim5, characterized in that the rotation of the polarization filter (4) canbe provided via appropriate means (7) directly by hand or else with theaid of a transmission mechanism, and in that, in particular, therotation of the filter (4) through at least 180 degrees is preferablypossible.
 7. The device (20) as claimed in claim 5, characterized inthat the polarization filter (4) can be rotated with the aid of a motor,and in that in this case the polarization filter (4) can be rotated witha rotation frequency in the range from 0.2 to 5 Hz, in particularpreferably with a rotation frequency from 0.5 to 2 Hz.
 8. The device(20) as claimed in claim 1, characterized in that the device isconfigured in the form of a pen which has a cylindrical housing toaccommodate at least one battery and a diode (18) and a lowercylindrical housing part (2), the lower housing part (2) forming a darkchamber (17) with an observation opening (10), with which the object (8)to be observed can be covered, the instrument (20) in particularpreferably having a length of less than 10 centimeters and, at itsthickest point, a diameter of less than 2.5 cm.
 9. The device (20) asclaimed in claim 8, characterized in that the observation opening (10)in the lower housing part (2) is formed in the form of a segment cutoutextending from the lower edge (11) of the lower housing part (2) with anopening angle in the range from 90 to 150 degrees with a height of lessthan 1.5 cm.
 10. The device (20) as claimed in claim 1, characterized inthat 2 groups of at least one UV light source or UV diode (18) in eachcase, preferably of 2 UV diodes (18) in each case, are arranged, and inthat these 2 groups irradiate the object (8) in a predefined,alternating manner, the first group (18 a) throwing a cone of light (12)with a first polarization direction onto the object (8), and the secondgroup (18 b) throwing a cone of light (12) with a second polarizationdirection onto the object (8), and the first polarization directionbeing aligned substantially perpendicular to the second polarizationdirection.
 11. The device (20) as claimed in claim 10, characterized inthat the UV light sources or UV diodes (18) are switched on and offalternately in groups, the change between the two groups being carriedout at a frequency of 0.2 to 5 Hz, in particular preferably at afrequency of 0.5 to 2 Hz.
 12. The device (20) as claimed in claim 10,characterized in that the UV light sources or UV diodes (18) of the 2groups are activated with a substantially sinusoidal intensity profile,the phase shift between the 2 groups being substantially 90 degrees. 13.The device (20) as claimed in claim 10, characterized in that there aretwo groups of respectively two UV light sources or UV diodes (18), ineach case UV light sources or UV diodes (18) belonging to one group (18a; 18 b) being arranged opposite each other in relation to theobservation axis and the two groups being arranged to be displaced by 90degrees around the observation axis.
 14. The device (20) as claimed inclaim 13, characterized in that a polarization filter is arranged infront of each UV light source or UV diode (18), the orientation of thepolarization direction of the polarization filters of the first group(18 a) being aligned substantially perpendicular to the orientation ofthe polarization direction of the polarization filters of the secondgroup (18 b).
 15. The device (20) as claimed in claim 13, characterizedin that a cylindrical polarization filter (30) is arranged betweenobject (8) and UV light sources or UV diodes (18), the axis of thecylindrical polarization filter (30) substantially coinciding with theobservation axis and the polarization direction of the UV light (12)passing through the polarization filter (30) likewise being arrangedparallel to the observation axis.
 16. The device (20) as claimed inclaim 15, characterized in that the cylindrical polarization filter (30)consists of a rolled polarization film.
 17. The device (20) as claimedin claim 10, characterized in that a holding arm (26) and an observationtube (21) are provided, the observation tube being aligned substantiallyat right angles to the holding arm (26).
 18. The device (20) as claimedin claim 1, characterized in that the observation is carried out througha lens, in particular preferably through a magnifying glass.
 19. Thedevice (20) as claimed in claim 1, characterized in that the observationis carried out by means of electronic aids, in particular in the form ofa recording device such as a camera, in particular a digital camera, ifappropriate in combination with a corresponding electronic visualizationmeans such as a display.
 20. The device (20) as claimed in claim 1,characterized in that the observation is carried out through apolarization filter which, in particular, preferably substantially doesnot permit light in the wavelength range of the UV diode (18) to pass,while light in the wavelength range of the photoluminescent light (16)from the segment can pass substantially only in a manner filtered withrespect to its polarization direction.
 21. The device (20) as claimed inclaim 1 one of the preceding claims, characterized in that means forverifying further security features are provided at the same time. 22.The device (20) as claimed in claim 21, characterized in that the meanspermit the verification of magnetic, electric, optical, electronic,electro-optical features, preferably selected from the group comprisingbar codes, magnetic strips, conductivity, electroluminescence,photoluminescence, up-conversion (anti-Stokes), infrared signatures,electronically readable texts, also including infrared text (OCR text),X-ray fluorescence features.
 23. A method of revealing security elementsthat are present in an object (8) and that have at least onephotoluminescent segment which is characterized by linearly polarizedabsorption, characterized in that light from at least ore light sourcein the form of a UV light source or preferably a UV diode (18) islinearly polarized (12) by at least one polarization filter (4), isincident on the object (8) or, respectively, on the photoluminescentsegments present therein in a dark chamber (17), and photoluminescentlight (16) in the visible range from the segment is observed through anobservation opening (10), the method being carried out in particularwith the aid of a device (20) as claimed in claim 1.